Production of superior solvents



y 28, 1942- .1. E. HARVEY, JR 4 2,291,313

PRODUCTION OF SUPERIQR SOLVENTS Filed March 14, 1941 war/114270 HMO/V ammo 0 Patented July 28, 1942 PRODUCTION OF SUPERIOR SOLVENTS Jacquelin E. Harvey, In, Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application March 14, 1941, Serial No. 383,463

9 Claims.

The present invention relates to the production of valuable solvents from tars and fractions thereof of aromatic content, crude and/or refined.

This application is a continuation in part of my application Ser. No. 345,445, filed July 13, 1940, for Production of superior solvents, copending herewith, as to all matter common to the two applications.

An object of the present invention is the production of superior solvents from tars, or fractions thereof, said production being characterized by being efiected in step-wise manner.

A further object of the present invention is a provision of increased boiling range and increased solvency.

Further object of the present invention is the production of solvents, the characteristics of which are, among other things, dependent upon hydrogen supply.

Other objects of the present invention will be apparent from the following disclosures.

Suitable starting materials of the present invention include tars and fractions thereof derived from coal, wood, petroleum or gas, as for instance coke oven tar, gas house tar, water gas tar, and tars of aromatic content derived from petroleum or fractions thereof; tars of aromatic content produced by cracking hydrocarbons or high boiling fractions resulting from the action of hydrogen on hydrocarbons; tars of aromatic content resulting from catalytic action on hydrocarbons, including polymerization; high boiling aromatic extracts of carbonaceous substances; high boiling hydrocarbons of olefinic and napththenic content; tars and fractions thereof of aromatic content.

Especially attractive as starting material is high temperature coke oven tar which is available in large quantities at low price.

The present invention may be broadly viewed as providing a process for the production of solvents by subjecting the starting material, in step-wise manner, to the controlled action of hydrogen, while contacting a catalytic material chosen from the group consisting of halids, halogens and derivatives thereof, whereby to produce solvents .of increased boiling range and enhanced solvency, as hereinafter described.

The starting materials of the present process are characterized by content of oxygenated organic compounds.

In my copending application Serial No. 345,439, dated July 13, 1940, is described a method for the substantially total conversion of tars and fractions thereof into solvents of superior quality,

said conversion being characterized by subjecting the starting material in step-wise manner to the controlled action of hydrogen.

It has been discovered that the process described in said copending application can be improved upon by the specific provision of means of influencing the decomposition of said oxygenated organic compounds contained in the starting material.

The following examples will serve to illustrate general principles upon which the practice of the present invention is based, as well as the process of the present invention.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the figure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example I.A coal tar boiling substantially 3% at 210 C. was passed through a high pressure reaction chamber at 400 C. and 200 atmospheres pressure. Catalysts, tin sulfide and iodoform. Time of contact was 1 hour. Gas flow was sufiicient to provide a beneficiated tar having lowered solvency, boiling range, specific gravity and viscosity. The thus beneficiated tar was distilled to 315 C. to recover in the order of 30% of the beneficiated tar as a distillate. The distillate was then passed through a high pressure reaction vessel at 475 C. and a pressure of 250 atmospheres with fiow of hydrogen so controlled as to provide a solvent, as compared to its intermediate parent material, having an increased boiling range, specific gravity, and solvency.

Example II.A residue from coal tar boiling substantially 3% at 380 C., Conradson carbon 14.5 and specific gravity 1.208 was passed through a high pressure reaction chamber at 410 C. and 300 atmospheres pressure; time of contact substantially 1 hour. Catalyst was molybdenum sulfide and tin chloride. Gas fiow sufiicient to provide a beneficiated tar fraction having a specific gravity of less than 1.06, a Conradson carbon of in the order of 4 and a lower solvency in some fractional parts than the starting material. The thus beneficiated tar fraction was stripped to 350 0., whereby to provide in the order of of the beneficiated material as a distillate. The distillate was then passed through a high pressure reactor at 460 C. and 300 atmos-- C. Benzol 78-120 Toluol 100-150 Hi-fiash naphtha 150-200 Plasticizers 160-360 The induced solvents may include lower boiling range than noted above.

The solvents of the present invention serve as good substitutes for the commercial solvents noted in the above tabular data.

Example III .It has been discovered that when subjecting certain mixtures of refined coal tar fractions to the action of hydrogen in accordance with the present process for the production of solvents and/or plasticizers that the formerly accepted teaching that product increment, depolymerization and/or hydrogen absorption are linear functions of the time, is not followed.

When subjecting a mixture of crude coal tar fractions boiling predominantly above 250 C. or 275 C. to the action of hydrogen, research has disclosed that the newly induced products, depolymerization and/or hydrogen absorption are linear functions of the time. As an' example,

when the above mixture of crude coal tar fractions is subjected to the action of hydrogen for 2-, 5-, and 8-hour periods, the newly induced products, depolymerization and/or hydrogen absorption were linear functions of the time element.

One of the preferred starting materials of the present process is a mixture of refined coal tar fractions boiling predominantly above 355 or 380 C. Such a starting material is conveniently the final residue resulting from evaporating coal tar to dryness or substantial dryness and then stripping wood preservative from the distillate. This final residue mass of refined coal tar fractions is an especially suitable refined coal tar pitch to be used as starting material of the present process. However, in contradistinction to the mixture of crude coal tar fractions boiling predominantly above 250 or 300 0., when the aforenamed preferred starting material is subjected to the action of hydrogen for production of solvents and/or plasticizers, the newly induced fractions, depolymerization and/or hydrogen absorption are not, as described for the mixture of crude coal tar fractions, linear functions of the time. A critical period of treatment by or with hydrogen exists, and which if exceeded causes loss of newly induced fractions, polymerization and/or lessened hydrogen absorption on certain fractions of the preferred starting material under treatment.

The critical time element because of the obvious possible variations in the characteristics of the aforenamed refined coal tar pitch cannot be spoken of as an arbitrary figure. It can be stated, however, that if the refined coal tar pitch were to be subjected to the action of hydrogen for such a length of time, which for other crude tar fractions would illustrate that the newly induced fractions, depolymerization and/or hydrogen absorption were linear functions of the time element, loss of induced products, polymerization and/or lessening of hydrogen absorption would occur. When treating the refined coal tar pitch by or with hydrogen, the critical time element is in the order of about three hours.

In the disclosures made herein and in the appended claims distillate removal of low boiling portions from the beneficiated material is considered the equivalent of fractional removal by gas movement, solvent action or the like. The converse also obtains.

The refined coal tar pitch chosen from the group boiling predominantly above, and above, 355 C. characterized by content of oxygenated compounds, a specific gravity in excess of 1 and a Conradson carbon in excess of about 4 is passed through a high pressure reaction chamber at 410 C. and 300 atmospheres pressure; time of contact substantially two hours; catalyst molybdenum sulfide and iodoform. The gas flow is held at about 18,000 cubic feet per barrel material treated. Thebeneficiated material will be found to be characterized by lowered oxygen content specific gravity, viscosity, Conradson carbon and a lowered solvency in some fractional parts as compared to the starting material. The thus beneficiated refined pitch is stripped to 300 C. to provide an intermediate starting material. The intermediate starting material, or a portion thereof, is passed through a high pressure reaction vessel with time, temperature, pressure and gas fiow so controlled as to induce a solvent having, as compared to the intermediate parent 7 material, an increased specific gravity at least in some portion thereof, boiling range and solvency. The thus treated material may if desired be fractionated to provide solvents including plasticizers of various boiling ranges.

When subjecting refined coal tar pitches to the action of hydrogen in accordance with the present process, the period of treatment in the first hydrogen action must be selected at or below the critical time period, otherwise loss of newly induced fractions and/0r polymerization will occur. The critical time element is in the order of about three hours. By employing a time period of treatment less than critical in the first hydrogen action, reaction conditions follow the accepted teaching that fractional increment, depolymerization and/or hydrogen absorption are linear functions of the time element.

In the foregoing examples, it will be noted that the present process provides a method for contacting heavy hydrocarbons, such as refined coal tar pitch, with hydrogen in the presence of a catalyst selected from a group consisting of halogens, halids and derivatives thereof, whereby to produce a product of lowered solvency, specific gravity, and boiling range; stripping from the beneficiatedmass a fraction, as for instance a fraction not including the highest boiling point; subjecting said lower boiling stripped material to the controlled action of hydrogen whereby to enhance solvency,-said enhanced solvency flowing from the "controlled action of hydrogen. o

Looked at in one manner, the present process provides a method for treating aromatic tars, or fractions thereof, with hydrogen in step-wise manner whereby to produce solvents, said solvents being characterized by increased solvency, specific gravity and boiling range when compared to an intermediate parent material, as hereto fore disclosed; the step-wise action of hydrogen being characterized by first providing hydrogen flow that depolymerizes ring multiplicities thereby inducing lowered specific gravity, boiling range and solvency, and second, by providing hydrogen in fiow that increases specific gravity, boiling range and solvency; a material influencing decomposition of oxygenated materials being present in at least one of said stages.

The aforenamed step-wise action of hydrogen thus provides a method for securing solvents of increased solvency and boiling range from heavy or high boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of ring multiplicities of great thermal susceptibility; and are further characterized by content of oxygenated organic compounds.

The starting materials of high carbon content, as for instance high temperature coke oven tar or fractions thereof, are characterized by, in their raw state, such a percentage of high molecular complexes 01' polymerized products that the solvents of the present invention, that is to say, solvents of increased boiling range and solvency, are not possible of manufacture directly therefrom, but must first be subjected to the controls of the present process wherein hydrogen flow, among other things, depolymerizes said molecular complexes.

The depolymerized or partially depolymerized tar or fractions thereof, is then stripped of a percentage of its low ends whereby to provide as a distillate the intermediate parent material of the solvents of increased boiling range and solvency. The residue incidental to said stripping may because of its depolymerized or partially depolymerized condition serve as material for recycle, with or without the addition of other starting material to the end that conversion of the starting material may approach volume for volume of said starting material into solvents of the present invention, neglecting manufacturing and gas loss.

In the conversion of the starting material, partially or approaching unity, into solvents of the present process, temperatures as low as 300 C. may be used; pressure as low as 50 atmospheres may be employed. However, temperatures and pressures of an increased range provide better commercial practice of the present invention. The time element is desirably that period which affords commercially recoveries of the products of, and incidental to, the present invention.

Flows of hydrogen or hydrogen containing gas are usually held in excess 2,000 cubic feet per barrel material treated. In the step-wise application of hydrogen whereby to provide the solvents of the present invention, a few trials when using any of this starting material will determine the gas fiow, when coordinated with the selected temperature and pressure conditions to effect aforesaid depolymerized conditions. The gas fiow in this instance may be variable quantity because of the varying ranges of coordinated temperature and pressure that may be selected. When using chosen coordination of temperature and pressure a few trials will readily determine the gas flow that provides depolymerizing conditions to the end that solvency, specific gravity, viscosity, and boiling range are lowered.

The gas flow that increases boiling range and solvency is held at that point that increases boiling range and solvency, thus providing the solvent products of the present invention. A few trials with any of the intermediate starting materials under chosen coordination of temperature and pressure will readily determine the desirable gas flow. For a given coordination of temperature and pressure the gas flow in the last instance is lower than the gas flow in the first instance.

Using some starting materials, a gas flow of from 10,000-15,000 cubic feet per barrel, or higher, has proven satisfactory for aforesaid depolymerizing conditions, and gas flows of in the order of 6,000-8,000 cubic feet, or lower, when increasing solvency and boiling range has proved satisfactory.

By the term beneficiated as used herein and in the appended claims is meant the starting or intermediate material at least once subjected to the action of hydrogen in accordance with the present invention.

After the starting tar has been subjected to depolymerizing action, as aforesaid, the stripping step may be eifected at any point selected within a Wide range to provide, after further processing, a cut capable of providing substitutes for conventional benzol, toluol, xylol, naphthas, and/or plasticizers.

Thus, the depolymerized starting material may be out according to the need at hand, said out then being subjected to the action of hydrogen that increases solvency and boiling range.

The residues resulting from any distillation step recited herein may be recycled for further solvent production.

In addition to aforementioned catalysts that influence the decomposition of oxygenated organic compounds contained in the starting material, various catalysts effective in the presence of hydrogen may be used. Catalysts chosen from the sixth and eighth periodic groups are effective. Especially effective are chromium, molybdenum, vanadium, uranium, cobalt, copper, and their compounds, as for instance their sulfides and/or oxides; promoted or not; with or without small amounts of alkali, acid or halogen or derivatives thereof; effective catalyst deposited on carriers, as for instance on gels, earths, carbon or the like; in various shapes, as for instance forms, extruded shapes or lengths, pellets, comminuted; mixed with other material effective in the presence of hydrogen or not; with or without the addition of material or materials eifecting splitting.

When using catalyst it may be desirable at times to use a comminuted catalyst during the period of the process characterized by depolymerization; thereafter, and during the period characterized by increase in solvency and boiling points, to use a rigid catalyst.

By the terms multiplicity of rings, high molecular complexes and polymerized products are meant high boiling fractions of aromatic content, a portion of which at least, may be viewed as ring multiples; or, said terms, any or all, may be used to describe high boiling fractions of the starting material which because of high carbon content are especially susceptible to thermal degradation. Fractions of the starting material contain oxygenated compounds and their depolymerization and/or elimination of oxygen is enhanced by the addition of said catalytic material that influences decomposition of said oxygenated compounds.

When subjecting high boiling fractions of aforenamed materials to the process of the present invention, it may be desirable prior to the depolymerizing step to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in small amounts, or up to volume for volume, or more may be used. Refractory solvents are desirable, but others more susceptible to the reactions inherent in and to the process are usable.

Concerning solvents, it may be said thattar, as for instance high temperature coke oven tar, comprises high molecular complexes dissolved, cut back or depolymerized with a solvent, said solvent being the lower boiling fractions of said tar.

The depolymerizing action of hydrogen, as aforestated, may be effected in one ormore cycles or chambers, with or without releasing the pressure and with or without variation of process controls, including changes in either temperature, pressure and/or gas control; the final action of hydrogen according to the present invention may be effected in one or more cycles or chambers with or without releasing pressure and with or without variation of process control, including changes in either temperature, pressure and/or gas fiow.

Various modes of practicing the present invention are possible; as for instance the depolymerized starting material may be stripped as for instance by gas movement; the low ends thus stripped may then with or without releasing pressure be subjected to the action of hydrogen that increases solvency and boiling points. Or the desired material may be obtained by partial release of pressure which corresponds to the fractional recovery desired or predetermined.

The process may be practiced in single high pressure chamber, a series thereof, parallelism thereof, including a multiplicity thereof.

The solvent of the present invention may, as aforestated, be fractionated to provide solvents of various boiling ranges, and in an instance where said solvents are processed from a deep cut on the depolymerized material, the highest boiling fraction of said deep cut may serve after further processing as plasticizing oils or the like.

From the foregoing disclosures it will be seen that the present invention provides a method for the production of solvents, characterized by subjecting oxygenated tar fractions boiling substantially above 190 C. to the action of hydrogen while contacting a catalyst selected from the group consisting of halids, halogens, and derivatives thereof, whereby to enhance the action of depolymerizing high molecular complexes and lowering of specific gravity, viscosity, solvency and boiling range; stripping therefrom a low boiling fraction and subjecting said low boiling fraction to the action of hydrogen that induces solvency.

The decomposition influencer which it is desired to have present in the reaction zone is generally taken between 0.1 and 4 or 5 percent, based on the feed stock, and is preferably taken between 0.1 and 1.5 percent.

Halogens, halids and derivatives thereof are employed for catalytic purposes noted in the foregoing; however, also may be employed substances furnishing under the process conditions a halogen or a hydrogen halid. Ammonium chloride may be employed, also halogen compounds of coal tar oils, or the like as for instance the iodides or bromides. Also may be employed acids such as nitric, sulphuric, sulphonic, formic and acetic.

The addition of the decomposition infiuencer may be made prior to the entry of the feed stock into the reaction chamber, or at any suitable time, as for instance after the charging stock has been heated.

Equivalent amounts of compounds furnishing halogen or hydrogen halid may be employed.-

The evaluation of solvent power is conveniently accomplished by finding the well-known aniline point or Kauributanol number. The evaluation of plasticizing properties is conveniently accomplished by recourse to methods suggested in Chapter VI, The Technology of S01- vents by Dr. Otto Jordon, Mannheim, Germany, translated by Alen D. Whitehead, Chemical Publishing Company of New York, Incorporated, New York, New York.

Minor changes may be made in the foregoing without departing from the spirit of the invention.

I claim: a

1. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen at a pressure and temperature in excess of 50 atmospheres and 30.0" C., respectively, while contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereby to avoid loss ofnewly induced fractions; stripping newly induced fractions from the beneficiated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated at a pressure and temperature of at least about 50 atmospheres and 460 C., respectively, to produce a solvent.

2. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen while contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated; and fractionating the last named beneficiated material to segregate a solvent. 7 r

3. In the production of a solvent from the re fined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly abov 355 C., the process which comprises: subjecting said higher boiling fraction to th action of a relatively high fiow of hydrogen whole contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereby to avoid loss of-newly induced fractions; stripping newly induced fractions from the beneficiated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated; and fractionating the last named beneficiated material to provide a solvent boiling preponderantly between 100 and 150 C.

4. In the production of a solvent from th refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen while contacting a catalyst selected from the group consisting thereof for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting the same to the action of a relatively low fiow of hydrogen not in excess of about 5000 cubic feet per barrel feed stock, to produce a solvent.

5. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen while contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof at a pressure in excess of about 50 atmospheres and a temperature in excess of about 300 C. for a period not in excess of about thre hours, whereby to avoid polymerization; stripping newly induced fractions from the beneficiated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated at a temperature and pressure of at least about 460 C. and 50 atmospheres, respectively, to produce a solvent.

6. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen at a temperature and pressure in excess of about 300 C. and about 50 atmospheres, respectively, while contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereb to avoid lowered hydrogen absorption; stripping newly induced fractions from the beneficiated material; and increasing the boiling points of at least a chosen portion of said stirpped fractions by subjecting same to the action of a relatively low fiow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated, to produce a solvent.

of halogens, halids and derivatives 7. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a woodpreservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen at a temperature and pressure in excess of 300 C. and 50 atmospheres, respectively, while contacting a catalyst selected from th group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; and increasing the specific gravity of at least a fractional part of a chosen portion of said stripped fractions by subjecting same to the action of a relativel low flow of hydrogen within the limits of about 2000- 5000 cubic feet per barrel material treated at a pressure and temperature of at least about 50 atmospheres and 460 C., respectively, to produce a solvent.

8. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen while contacting a catalyst selected from the group consistlng of halogens, halids and derivatives thereof at a pressure in excess of about 50 atmospheres and a temperature in excess of about 300 C, for a period not in excess of about three hours, whereby to avoid polymerization; stripping newly induced fractions from the beneficiated material; and increasing the specific gravity of at least a fractional part of a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated at a temperature and pressure of at least about 460 C. and 50 atmospheres, respectively, to produce a solvent.

9. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen while contacting a catalyst selected from the group consisting of halogens, halids and derivatives thereof at a temperature and pressure in excess of about 300 C. and about 50 atmospheres, respectively, for a period not in excess of about three hours, whereby to avoid lowered hydrogen absorption; stripping newly induced fractions from the beneficiated material; and increasing the specific gravity of at least a fractional part of a chosen portion of said stripped fractions by subjecting sam to the action of a relatively low fiow of hydrogen within the limits of about 2000-5000 cubic feet per barrel material treated at a temperature of at least 460 C., to produc a solvent.

JACQUELIN E. HARVEY, JR. 

